Mark - full fuel and two people only allows 300lbs to gross in a cj3+? I assumed full fuel payload was at least 1000-1100lbs.

Also, the book speeds on the cj3 seem slower than what everyone says. Operators all says it’s 400krs all of the time but the book doesn’t seem to support that.

400 knots all day long with the exception of a really cold ISA which brings .737M to sub 400 TAS. I've seen as high as 425TAS with a warm isa in the mid 30s.

As you note, Textron's numbers are conservative and you can often find the planes outperform the numbers by 3-4% naturally.

None the less, the Tamarack marketing claims, like 33% fuel saved, don't align with their own performance numbers. So not only are they lying, they know it.

Mike C.

Yes. I studied them a bit when I first considered a CJ2 with the new Garmin panel as my range extending upgrade path. Let’s just say I'm not a Tamarack winglet fan, on a few accounts:

1. Over the last 1/2 dozen years, there have been a similar number of incidents (5? 6?) where a Tamarack winglet equipped plane experienced an uncommanded roll over, a winglet that departed the plane, and/or a fatal crash with an unexplained roll over. As best I can tell, there are no similar reports for non-winglet Citations. Either Tamarack equipped airplanes are statistically unlucky, or something is amiss.

2. To my ear, their claims of performance improvements seem to have a bit of puffery. I can see where the winglets might provide some extra lift, and provide “some” degree of performance enhancements in the high flight levels, particularly as the plane transitions to the highest cruise altitude, and accelerates to cruise speed. However, the CJ3 is so highly powered, that you never need to step climb, and the timeframe from leveling to hitting the max KIAS, is quite short. I don’t see how the juice is worth the squeeze, particularly in the CJ3. It reminds me of an energy saving product for the residential home market, that claimed “millions of BTU’s in annual energy savings”. In fossil fuel terms, a million BTU’s is somewhere between 7 and 10 gallons. The claim is true, but the actual $ benefit was negligible.

3. I think winglets are a love ‘em or hate ‘em sort of product. I think some buyers (like me) will simply bypass a plane with winglets. From a future marketing standpoint, I wouldn’t want a product on my plane that might alienate some potential buyers.

I’m not saying that winglets are definitively unsafe, nor am I disputing that they might offer “some” amount performance benefit. However, I’m skeptical by nature, and particularly skeptical in this instance.

I think the book numbers are a bit slow, but at FL450, it is not 400 KTAS "all the time", at least in my plane. Generally speaking, (but with somewhat limited experience) I almost always find the ISA temps at FL450 to average right around ISA. Rarely do I see it exceed +/- 10 ISA. Looking back at a recent flight that averaged ISA, I tend to see 395 TAS on average, based on the FlySto data. Often above 400, but not "always" above 400. That said, I frequently have to pull the power back, because MMO is .737 mach, and it is not uncommon with a bit a atmospheric wave to run exceed the barber pole if you aren't paying attention. Of course, I am "always" paying attention.

Damn. I don't even see where any of the book numbers can get that high, even in the mid 30's. (that said, I almost always fly higher)

More wax on mine I guess.

That said, I know a warm ISA will allow a higher TAS for a given mach number, but doesn't a warm ISA also correspond to reduced thrust? It seems to me these engines are optimized for ISA temps, and temps that that go above ISA tend to reduce thrust and KTAS, while temps that go below ISA might get mach limited. At least it looks that way to me, based on AFM performance data. Snippets from the AFM at FL350 and FL 450 below. I stack bricks for a living, so my assumptions may be incorrect.



45,000 ft chart below:

You are correct that a warm isa corellates to reduce thrust. In the CJ and mustang that can really rob you of performance. In the CJ2+/CJ3/3+ I find them almost overpowered and I occasionally hunt for isa+ at altitude, within reason, to enjoy the faster true airspeeds as I know I've got the power to hit Mmo.

Unless absurd headwinds I'm usually at FL410 or FL430 in the 2+ or 3+ with zero worries about performance at those altitudes. FL450 I'll still usually see the barber pole but it may take a few extra minutes to get there if I'm heavy or if it's isa+ much. If I saw something relatively high such as isa +10 I'd probably avoid FL 450.

In the event there are crazy headwinds, they almost always start to die above FL430 anyway.

You're sipping fuel up there!

Wow. I thought on the jets the LRC was always pretty close to the max speed at high altitudes. It would appear that is not the case in the cj3. That is some good nm/lb numbers when you pull it back!

Sounds like it needs service? I complain if it’s more than 3 degrees from selected to actual?

It is at max weight, that chart is 10,000

Andrew

Call me crazy, but if it only has 300 pounds of full fuel useful load because it can hold more fuel, I'm all in for that. Our Phenom 100 has 960 pounds of full fuel payload, but I'd much rather have the ability to add another 500 pounds of fuel.

Chip-

Call me crazy, but if it only has 300 pounds of full fuel useful load because it can hold more fuel, I'm all in for that. Our Phenom 100 has 960 pounds of full fuel payload, but I'd much rather have the ability to add another 500 pounds of fuel.

Chip-

The payload question is misleading - what matters is carrying what how far.

For a plane like a cj3, I want to carry 8 not super heavy people 1400nm no matter what. That requires darn near the full fuel published range numbers in legit winter winds. Hence why I was asking about full fuel payload.

The jet range gets really punished if you cannot get to FL450 from all the profiles I have run. Nice to see cj3 can blast up there no matter what.

Piaggio carries a lot at full fuel. Newer ones can add an extra tank which cuts payload but increases range. I would love to have that but it doesn’t fit on old ones like mine. 1900nm range is the killer app for a plane imo.

I can't find 8 people I like that much.